The principle of similitude (Rayleigh 1915) or dimensional homogeneity, states that only commensurable quantities (ones having the same dimension) may be compared, therefore, meaningful laws of nature must be homogeneous equations in their various units of measurement, a result which was formalized in the Π theorem (Vaschy 1892; Buckingham 1914). In other words, meaningful laws of nature must be independent of the units employed to measure the variables (Fourier 1822). However, in many areas such as Biology, Economics or even partially in Astronomy (a subbranch of Physics), the most fundamental empirical relations do not satisfy this basic mathematical requirement. In this talk, we show (using the Π theorem) that it is indeed  possible to construct homogeneous equations to describe as diverse phenomena such as the star formation rate in galaxies (Astronomy) and the metabolic rates of animals (Biology), in agreement with data in the literature (Utreras, Becerra & Escala 2016; Escala 2018).